Evidence has been obtained suggesting: 1) the presence of a high concentration of copper ions in purified preparations with angiogenesis activity, both from tumor extracts and normal tissues; 2) a stimulatory action of copper ions on the migration of endothelial cells in vitro and 3) angiogenic activity of PGE1. The objective of this work is to verify in vivo the role of copper ions during neovascularization induced by PGE1.